Body problems of the 2016 Buick Encore

My drivers side door began to have a few small bubbles around the handle. I took it in and found out the door was rusting from the inside. Rain was getting in and rusting the sound bar. I paid $350 only to find out that the bubbles began to reappear in a few days. When the Buick dealer took it back it, they discovered the problem. They said it was rusting inside the the door and that I needed a new door and that it was covered under corrosion. I want my $350 back due to the fact that it was covered and I never should have to pay $350.

Service light came on after being on the highway car started pulsing and now my car is idling rough.

I purchased 2016 Encore on 5/7/16. While on a 300 mile road trip on 7/2 /16 notice the exhausted pipe was melted to the bumper took pictures. Called the number to extended warranty and they weren't able to help me due to holiday weekend. Drove it back home stop every hour to make sure it wasn't going to start my car on fire. Took it to the dealership the next day 7/ 5 I told them I don't feel safe in the vehicle. They said why would look into what cause it. The dealership has there own picture this incident in not in dispute. They said GMC been contacted and no other incident has been reported. They gave me a loaner on 7/5 the mechanic manager said he put the vehicle on lift doesn't see anything wrong with it he said he will have his very mechanic look at it on 7/6 called that day to update me that GMC is involved and will keep me informed. Called me on 7/7 with same updated that they are still looking into it. On 7/12 called back and said they could not duplicated the problem. So it was decided to replace part of the bumper and return the vehicle to me I stress that I don't feel safe with this vehicle I'm about to drive to florida in a couple of week and the problem happen on a long distance and not short distances. Called customer service and was told the dealership is not going to help me out. I ask if they could give me documentation to what they found and he said no cause we couldn't duplicate the problem. That was eight days ago I haven't heard from them since 7/12. I called customer service back on 7/20 and she told me that the dealership is fixing the bumper and giving it back to me. I feel this is a brand new vehicle and this should not have happen and seem like a factory defect that they want to put a band aid and send me on my way. I asked customer service did they take it on a long ride to test it out and she could not answer the question.